This invention relates to a laser beam level instrument of the kind used in surveying and in the construction industry. It relates particularly to a relatively lightweight, portable, self-contained level which can be carried by one man and which, in operation, functions to provide self-leveling within a certain range of angular tilting of the laser beam level instrument. The beam is subsequently detected by a portable electronic detector.
The laser beam level instrument of the present invention is constructed to be used as a replacement for optical and other automatic level instruments now used in construction.
Laser beam level instruments are instruments which sweep a laser beam in a horizontal plane and are used in surveying and in the construction industries. Tube type gas lasers are often used as the light source, and the output beam of the gas laser is usually aligned vertically and then deflected to the horizontal by rotating heads which sweep, or swing, the horizontal beam in a horizontal plane. U.S. Pat. No. 4,062,634 to Rando, el al. (and assigned to the same Assignee as the Assignee of this application) gives a detailed description of a prior art laser level which uses a gas laser tube as the light source.
A laser level should be capable of providing a certain amount of automatic self-leveling to maintain the beam in a horizontal plane after the laser beam level instrument is initially set up and turned on. The base or stand on which the instrument is supported in the field may be bumped or otherwise caused to shift to at least a slight amount in the course of operations, and self-leveling eliminates the need for an operator to manually readjust the level each time it gets such a slight bump or jar.
Automatic self-leveling also makes initial set-up faster since precise adjustments are not required for the initial set-up.
The helium-neon lasers used as the light source in prior art laser beam level instruments are relatively big and, as a result, the prior art laser levels have tended to be relatively large and heavy devices which required servomotors and large power packs to provide plasma tube power and the desired self-leveling. These prior art laser beam level instruments have often been too large to be carried by one person, and were also relatively expensive to manufacture and to buy.